Every ant, every spider you see has these strange little teeth...
Why do leaf cutter ants wait until they reach a certain age to start cutting leaves? The answer may be that zinc has not been incorporated into their mandibles. The ant to the upper right in the image below is a young leaf cutter in the nest and the ant to the left is an older one at work on a leaf. Below the ants you see high energy ion microscopy images of their mandibles. These pictures are like x-ray images for different elements. The young mandible is the one to the left and the mature one is to the right in the three bottom images. Note the lack of zinc in the young mandible shown in image c.
Broader impact of our research:
The mechanism by which so much metal is loaded homogenously into the cuticle may have useful applications in biomimetic materials, as may the high degree of wear resistance that it apparently confers. This research may also have application in agricultural pest control. But the most important broader impact is on our basic understanding of life: even most biologists are completely unaware of this bizarre inorganic biochemistry that has, by simply increasing resistance to wear, likely affected the evolution, behavior and possibly the life span of the majority of invertebrates that humans encounter.